The U.S. Food and Drug Administration and the Centers for Disease Control and Prevention are widening their investigation into a cyclosporiasis outbreak linked to shredded iceberg lettuce from central Mexico after identifying cases in four additional states.

CDC confirms 4,173 U.S. Cyclospora cases as it investigates a lettuce-linked outbreak. More than 7,400 additional reports remain under review.

The FDA is investigating at least five other clusters of cyclosporiasis, including an outbreak of 72 cases reported by the agency on Wednesday.

Investigators believe additional states will help them better construct how cyclosporiasis moved through the nation's food supply.